It is generally known to provide a vehicle seat cushion for the comfort of an occupant of a vehicle, such as an automobile. Typically, it is known to formulate such a seat cushion from a polyurethane-based foam. Such foam may be formulated to be relatively soft and still provide a relatively high comfort level (e.g. “luxury feel”) for an occupant. However, such soft foam may not always be sufficiently effective at dampening road vibration generated during movement of the automobile. To overcome this problem, a harder or more firm foam may be provided in the seat cushion to better dampen road vibration. However, such firm foams may provide less “cushion” and comfort (particularly over a longer period of time) relative to such soft foam.
It is also generally known to prepare such a polyurethane-based foam cushion according to a “one shot” process. In a one shot process, such generally known soft and firm polyurethane foams are typically formed from a mixture of a first (or polyol) stream and a second (or Isocyanate) stream. The polyurethane-based foam is typically composed of a polyurethane-based base polyol resin, a polyurethane-based copolymer polyol resin (co-polyol), water, a catalyst (or catalyst package, typically an isocyanate such as TDI or TM20) and a surfactant. The polyol stream is generally composed of a polyurethane polymer with a propylene oxide (PO) that may be manufactured with potassium hydroxide (KOH) and/or then ethylene oxide (EO) capped. Other generally known methods of manufacturing polyols include the use of Cobalt and Zinc Hydroxide, cesium hydroxide (CsOH), Iridium and rubidium hydroxide (RbOH). Such polyols can be made with or without EO capping. Other known methods of manufacture of polyols, which are not EO capped, includes using heavy metal cyanide complexes.
Such known soft and firm polyurethane foams may also be formed from a process of mixing the following components: a pre-polymer (e.g. a combination of a copolymer polyol and a base polyol such as the Acclaim™ polyol and Hyperlite XL™ synthetic resin commercially available from Bayer Corporation of Pittsburgh, Pa.), copolymer polyol, that may be PO capped only, water, catalyst, surfactant and an isocyanate.
It is generally understood to mix the components by pouring the two streams into a mold tool, closing the mold tool, and allowing the components to react. Heat may be optionally applied to the mold to help reduce the amount of time to cure the foam and thereby more quickly produce a foam article. After the foam is fully cured (e.g. after about 2 to 60 minutes—depending upon the amount of capital investment and part production time allowed), the foam article is removed from the mold (i.e. “demold”) and is crushed (and may be repeatedly crushed) using a predetermined force to obtain a predetermined amount of reduction in size at a particular time (e.g. from 15 seconds to 8 minutes after demold). However, a problem with such generally known process is that the resulting foam article also is not always sufficiently effective at dampening road vibration generated during movement of the automobile. Further, there is a challenge with the generally known polyurethane formulations to use different base polyurethane resin materials in the base and/or in the copolymer polyol while still providing comparatively similar and/or improved performance characteristics.
It would be advantageous to provide a method for making polyurethane foam that permits control of performance characteristics of the foam. It would also be advantageous to provide a polyurethane foam having vibration dampening properties and suitable comfort that can be specifically tailored and applied to particular vehicle components including sub-components of a vehicle seat which allows for a broader variety of polyurethane resins materials to be used as part of the base polyol and/or the copolymer polyol. It would also be advantageous to provide such a polyurethane foam with such improved performance characteristics to allow for a reduction in need for other vibration reduction sub-systems in a vehicle (e.g. shocks, tires, springs, etc.). There remains a continuing need and it would be advantageous to provide such a polyurethane foam including a system or method having any one or more of these or other advantageous features.